1. Field of the Invention
The present invention relates to a method of producing a shaft and particularly to a shaft for a golf club, fishing pole, etc. that is superior in strength as well as in resilience.
2. Prior Art
The conventionally manufactured shafts for golf clubs, fishing poles, etc. include those made of high strength carbon fibers, in addition to those made of metal. However, such carbon fiber shafts have been disadvantageous in that they are inferior to the metal shafts in strength and resilience.
It has also been known that two carbon cloth tapes may be wound around a shaft in the opposite direction so that the two tapes come across each other to form a uniform pattern with crossing portions. Such crossing portions are formed every 180 degrees around the shaft (FIG. 1). This will improve the strength of the shaft with those crossing portions. However, since those crossing portions are located only every 180 degrees, the strength and the resiliency of the shaft are uneven. Particularly, the shaft shows weakness when tension is applied in the direction where there are no crossing portions.
Taking golf clubs, for example, golf clubs are divided into two types. One is usually called "wood clubs"; and the other is called "iron clubs". A golf club set is comprised of three or four wood clubs and seven to nine iron clubs in addition to a putter.
As shown in FIG. 2, a golf club has a head b at the end of a shaft a. For each of the clubs, the length and the weight are preliminary specified. To obtain a strong shot, it is desirable to make the club head heavier while making the club shaft lighter for offsetting the weight increase in the head. However, it is difficult to make the shaft light while maintaining the strength and the resiliency of the shaft.